This invention relates to accelerators that may be useful for energy polymerizable compositions comprising a cationically curable material; energy-polymerizable compositions that comprise a cationically curable material and a two-component initiator system, which initiator system comprises at least one organometallic complex salt and at least one accelerator; and a method for curing the compositions. This invention also relates to preparing articles comprising the cured compositions. In addition to other uses, the compositions are useful as molded articles, as coating compositions including abrasion resistant coatings, as adhesives including structural adhesives, and as binders for abrasives and magnetic media. The invention also relates to compositions of matter comprising an organometallic complex salt and at least one compound selected from the Class 1 through Class 4 compounds disclosed herein.
Transition metal salts comprising an organometallic cation and a non-nucleophilic counteranion have been shown to have utility as photochemically activated initiators for cationic addition polymerization. These photoinitiator salts include (cyclopentadienyl) (arene) iron+salts of the anions PF6xe2x88x92and SbF6xe2x88x92. Similarly, certain classes of these salts are known to be thermally-activatable curatives for cationic polymerizations.
For many commercial applications, the monomers being polymerized are often multifunctional (i.e., contain more than one polymerizable group per molecule), for example, epoxides, such as diglycidyl ethers of bisphenol A (DGEBA). Mixtures of multifunctional monomers such as epoxides and polyalcohols (polyols) or polyepoxides and polyalcohols can undergo acid-catalyzed polycondensation via a step-growth mechanism. Also included in this description are multireactive monomersxe2x80x94those that comprise two or more classes of reactive groups.
In many applications photoinduced polymerization is impossible, impractical or undesirable. For example, many situations where polymerization reactions occur in a closed environment (i.e., in a mold or in a laminated product) or where polymerizable compositions may contain opacifying pigments, thermally activated initiators are preferred. Thermally-activated initiators, such as known organometallic salts, may be used to initiate polymerization in these cases.
There is a continuing need to be able to modify the rate and temperature of polymerization of energy polymerizable compositions to meet the needs of specific applications.
The present invention relates to accelerators that may be used to influence the temperature at which the polymerization of an energy polymerizable composition comprising a cationically curable material occurs. In particular, the accelerators of this invention may be used to reduce the polymerization temperature or allow modification of the rate or degree of polymerization at a given temperature of cationically-polymerizable materials when organometallic salt initiators are used in cationic polymerization.
Briefly, in one aspect, this invention provides a method comprising the step of using at least one accelerator and at least one salt of an organometallic complex cation to increase the rate, or reduce the temperature, of cure of an energy polymerizable composition comprising a cationically curable material, wherein said cation contains at least one carbon atom bonded to a transition metal atom, and wherein said accelerator, or an active portion thereof, comprises at least one compound selected from classes 1 through 4
class 1 comprises compounds represented by Formula III,
class 2 comprises compounds represented by Formula IV,
class 3 comprises compounds represented by Formula V, and
class 4 comprises compounds represented by Formula VI.
In another aspect this invention provides an energy polymerizable composition comprising:
(a) at least one cationically curable material;
(b) a two-component initiator system comprising:
(1) at least one salt of an organometallic complex cation, wherein said cation contains at least one carbon atom bonded to a transition metal atom, and
(2) at least one accelerator, or an active portion thereof, of classes 1, 2, 3, and 4 wherein class 1 comprises compounds represented by Formula III, class 2 comprises compounds represented by Formula IV, class 3 comprises compounds represented by Formula V, and class 4 comprises compounds represented by Formula VI herein.
In other aspects, the invention provides an energy polymerizable composition with one or more of the following optional components:
(a) at least one of an alcohol-containing material and additional adjuvants;
(b) stabilizing ligands to improve shelf-life;
(c) at least one film-forming thermoplastic oligomeric or polymeric resin essentially free of nucleophilic groups, such as amine, amide, nitrile, sulfur, or phosphorous functional groups or metal-complexing groups, such as carboxylic acid and sulfonic acid; and
(d) coupling agents to modify adhesion.
In another aspect, the invention provides a process for controlling or modifying the cure of a composition comprising the steps of:
(a) providing the energy polymerizable composition of the invention,
(b) adding sufficient energy to the composition in the form of at least one of heat, radiation, and light, in any combination and order, to polymerize the composition.
In another aspect, this invention provides an article comprising a substrate having on at least one surface thereof a layer of the composition of the invention. The article can be provided by a method comprising the steps:
(a) providing a substrate,
(b) coating the substrate with the curable composition of the invention and, optionally, adjuvants; and
(c) supplying sufficient energy to the composition in the form of at least one of heat, radiation, and light in any combination and order to polymerize the composition.
In another aspect, this invention provides a composition of matter comprising
(1) at least one salt of an organometallic complex cation, wherein said cation contains at least one carbon atom bonded to a transition metal atom, and
(2) at least one compound, or an active portion thereof, from classes 1, 2, 3, and 4 wherein class 1 comprises compounds represented by Formula III, class 2 comprises compounds represented by Formula IV, class 3 comprises compounds represented by Formula V, and class 4 comprises compounds represented by Formula VI herein.
As used in this application:
xe2x80x9cenergy-induced curingxe2x80x9d means curing or polymerization by means of heat or light(e.g., ultraviolet and visible), radiation (e.g., electron beam), or light in combination with heat means, typically such that heat and light are used simultaneously, or in any sequence, for example, heat followed by light, light followed by heat followed by light;
xe2x80x9ccatalytically-effective amountxe2x80x9d means a quantity sufficient to effect polymerization of the curable composition to a polymerized product at least to a degree to cause an increase in viscosity of the composition under the conditions specified;
xe2x80x9corganometallic saltxe2x80x9d means an ionic salt of an organometallic complex cation, wherein the cation contains at least one carbon atom of an organic group that is bonded to a metal atom of the transition metal series of the Periodic Table of Elements (xe2x80x9cBasic Inorganic Chemistryxe2x80x9d, F. A. Cotton, G. Wilkinson, Wiley, 1976, p. 497);
xe2x80x9cinitiatorxe2x80x9d and xe2x80x9ccatalystxe2x80x9d are used interchangeably and mean at least one salt of an organometallic complex cation that can change the speed of a chemical reaction;
xe2x80x9ccationically curable monomerxe2x80x9d means at least one epoxide containing or vinyl ether containing material;
xe2x80x9cpolymerizable compositionxe2x80x9d or xe2x80x9ccurable compositionxe2x80x9d as used herein means a mixture of the initiator system and the cationically curable monomer; alcohols and adjuvants optionally can be present;
xe2x80x9cpolymerizexe2x80x9d or xe2x80x9ccurexe2x80x9d means to supply sufficient energy to a composition in the form of at least one of heat, radiation, and light in any order or combination to alter the physical state of the composition, to make it transform from a fluid to less fluid state, to go from a tacky to a non-tacky state, to go from a soluble to insoluble state, or to decrease the amount of polymerizable material by its consumption in a chemical reaction;
xe2x80x9cinitiation systemxe2x80x9d, xe2x80x9cinitiator systemxe2x80x9d, or xe2x80x9ctwo-component initiatorxe2x80x9d means at least one salt of an organometallic complex cation and at least one accelerator, the system being capable of initiating polymerization;
xe2x80x9cacceleratorxe2x80x9d, xe2x80x9caccelerating additivexe2x80x9d means at least one of member of a specified class of compounds that moderate the cure of a composition of the invention by reducing the polymerization temperature or allowing an increase of the rate or degree of polymerization at a given temperature;
xe2x80x9cepoxy-containingxe2x80x9d means a material comprising at least one epoxy and may further comprise accelerating additives, stabilizing additives, fillers, diols, and other additives;
xe2x80x9cgroupxe2x80x9d or xe2x80x9ccompoundxe2x80x9d or xe2x80x9cligandxe2x80x9d means a chemical species that allows for substitution or which may be substituted by conventional substituents which do not interfere with the desired product, e.g., substituents can be alkyl, alkoxy, aryl, phenyl, halo (F, Cl, Br, I), cyano, nitro, etc., and
xe2x80x9cepoxy/polyolxe2x80x9d and xe2x80x9ccatalyst/additivexe2x80x9d, etc., mean combinations of the substances on both sides of the slash (xe2x80x9c/xe2x80x9d).
An advantage of at least one embodiment of the present invention is that the initiator system can initiate curing of a thermally- or photo- polymerizable composition at temperatures lower than temperatures required for reactions initiated without the accelerators of the present invention.
Another advantage of at least one embodiment of the invention is that the initiator system can provide enhanced curing of a thermally- or photo-polymerizable composition at a given temperature. For example, at a given temperature, curing time can be reduced as compared to curing times for reactions initiated without the accelerators of the invention.
The present invention provides an energy polymerizable composition comprising at least one cationically-polymerizable material and an initiation system therefor, the initiation system comprising at least one organometallic complex salt and at least one accelerator. The cured composition provides useful articles or coated articles.
Epoxy compounds that can be cured or polymerized by the processes of this invention are those known to undergo cationic polymerization and include 1,2-, 1,3-, and 1,4-cyclic ethers (also designated as 1,2-, 1,3-, and 1,4-epoxides).
See the xe2x80x9cEncyclopedia of Polymer Science and Technologyxe2x80x9d, 6, (1986), p. 322, for a description of suitable epoxy resins. In particular, cyclic ethers that are useful include the cycloaliphatic epoxies such as cyclohexene oxide and the ERL series type of resins available from Union Carbide, New York, N.Y., such as vinylcyclohexene oxide, vinylcyclohexene dioxide, 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexane carboxylate, bis-(3,4-epoxycyclohexyl) adipate and 2-(3,4-epoxycylclohexyl-5,5-spiro-3,4-epoxy) cyclohexene-meta-dioxane; also included are the glycidyl ether type epoxy resins such as propylene oxide, epichlorohydrin, styrene oxide, glycidol, the EPON series type of epoxy resins available from Shell Chemical Co., Houston, Tex., including the diglycidyl either of bisphenol A and chain extended versions of this material such as EPON 828, EPON 1001, EPON 1004, EPON 1007, EPON 1009 and EPON 2002 or their equivalent from other manufacturers, dicyclopentadiene dioxide, epoxidized vegetable oils such as epoxidized linseed and soybean oils available as VIKOLOX and VIKOFLEX resins from Elf Atochem North America, Inc., Philadelphia, Pa., epoxidized KRATON LIQUID Polymers, such as L-207 available from Shell Chemical Co., Houston, Tex., epoxidized polybutadienes such as the POLY BD resins from Elf Atochem, Philadelphia, Pa., 1 ,4-butanediol diglycidyl ether, polyglycidyl ether of phenolformaldehyde, epoxidized phenolic novolac resins such as DEN 431 and DEN 438 available from Dow Chemical Co., Midland Mich., epoxidized cresol novolac resins such as ARALDITE ECN 1299 available from Ciba, Hawthorn, N.Y., resorcinol diglycidyl ether, and epoxidized polystyrene/polybutadiene blends such as the EPOFRIEND resins such as EPOFRIEND A1010 available from Daicel USA Inc., Fort Lee, N.J., and resorcinol diglycidyl ether.
The preferred epoxy resins include the ERL type of resins especially 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate, bis-(3,4-epoxycyclohexyl) adipate and 2-(3,4-epoxycylclohexyl-5,5-spiro-3,4-epoxy) cyclohexene-meta-dioxane and the bisphenol A EPON type resins including 2,2-bis-[p-(2,3-epoxypropoxy)phenylpropane and chain extended versions of this material. It is also within the scope of this invention to use a blend of more than one epoxy resin. The different kinds of resins can be present in any proportion.
It is within the scope of this invention to use vinyl ether monomers as the cationically curable material. Vinyl ether-containing monomers can be methyl vinyl ether, ethyl vinyl ether, tert-butyl vinyl ether, isobutyl vinyl ether, triethyleneglycol divinyl ether (RAPI-CURE DVE-3, available from International Specialty Products, Wayne, N.J.), 1,4-cyclohexanedimethanol divinyl ether (RAPI-CURE CHVE, International Specialty Products), trimetylolpropane trivinyl ether (TMPTVE, available from BASF Corp., Mount Olive, N.J.) and the VECTOMER divinyl ether resins from Allied Signal, such as VECTOMER 2010, VECTOMER 2020, VECTOMER 4010, and VECTOMER 4020, or their equivalent from other manufacturers. It is within the scope of this invention to use a blend of more than one vinyl ether resin.
It is also within the scope of this invention to use one or more epoxy resins blended with one or more vinyl ether resins. The different kinds of resins can be present in any proportion.
Bifunctional monomers may also be used and examples that are useful in this invention possess at least one cationically polymerizable functionality or a functionality that copolymerizes with cationically polymerizable monomers, e.g., functionalities that will allow an epoxy-alcohol copolymerizaton.
When two or more polymerizable compositions are present, they can be present in any proportion.
Suitable salts of organometallic complex cations of the initiator system include, but are not limited to, those salts disclosed in U.S. Pat. No. 5,089,536, (col. 2, line 48, to col. 16, line 10), which patent is incorporated herein by reference in its entirety.
In preferred compositions of the invention, the organometallic complex salt of the initiator system is represented by the following formula:
[(L1)y(L2)zM]+q Xnxe2x80x83xe2x80x83(I)
wherein
M is selected from the group comprising Cr, Ni, Mo, W, Mn, Tc, Re, Fe, Ru, Os, Co, Rh and Ir;
L1 represents the same or different ligands contributing pi-electrons that can be selected from aromatic compounds and heterocyclic aromatic compounds, and the ligand is capable of contributing six pi-electrons to the valence shell of M;
L2 represents the same or different ligands contributing pi-electrons that can be selected from cyclopentadienyl and indenyl anion groups, and the ligand is capable of contributing six pi-electrons to the valence shell of M;
q is an integer having a value of 1 or 2, the residual charge of the complex cation;
y and z are integers having a value of zero, one, or two, provided that the sum of y and z is equal to 2;
X is an anion selected from tris-(highly fluorinated alkyl)sulfonyl methide, bis-(highly fluorinated alkyl)sulfonyl imide, tris-(fluorinated aryl)sulfonyl methide, tetrakis-(fluorinated aryl) borate, organic sulfonate anions, and halogen-containing complex anions of a metal or metalloid; and
n is an integer having a value of 1 or 2, the number of complex anions required to neutralize the charge q on the complex cation.
Ligands L1 and L2 are well known in the art of transition metal organometallic compounds.
Ligand L1 is provided by any monomeric or polymeric compound having an accessible aromatic group regardless of the total molecular weight of the compound. By xe2x80x9caccessiblexe2x80x9d, it is meant that the compound (or precursor compound from which the accessible compound is prepared) bearing the unsaturated group is soluble in a reaction medium, such as an alcohol, e.g., methanol; a ketone, e.g., methyl ethyl ketone; an ester, e.g., amyl acetate; a halocarbon, e.g., trichloroethylene; an alkane, e.g., decalin; an aromatic hydrocarbon, e.g., anisole; an ether, e.g., tetrahydrofuran; or that the compound is divisible into very fine particles of high surface area so that the unsaturated group (that is, the aromatic group) is sufficiently close to the metal to form a pi-bond between that unsaturated group and M. By polymeric compound, is meant, as explained below, that the ligand can be a group on a polymeric chain.
Illustrative of ligand L1 are substituted and unsubstituted carbocyclic and heterocyclic aromatic ligands having up to 25 rings and up to 100 carbon atoms and up to 10 heteroatoms selected from nitrogen, sulfur, non-peroxidic oxygen, phosphorus, arsenic, selenium, boron, antimony, tellurium, silicon, germanium, and tin, such as, for example, eta6-benzene, eta6-mesitylene, eta6-toluene, eta6-p-xylene, eta6-o-xylene, eta6-m-xylene, eta6-cumene, eta6-durene, eta6-pentamethylbenzene, eta6-hexamethylbenzene, eta6-fluorene, eta6-naphthalene, eta6-anthracene, eta6- perylene, eta6-chrysene, eta6-pyrene, eta6-triphenylmethane, eta6-paracyclophane, and eta6-carbazole. Other suitable aromatic compounds can be found by consulting any of many chemical handbooks.
Illustrative of ligand L2 are ligands derived from the substituted and unsubstituted eta5-cyclopentadienyl anion, for example, eta5-cyclopentadienyl anion, eta5-methylcyclopentadienyl anion, eta5-pentamethylcyclopentadienyl anion, eta5-trimethylsilylcyclopentadienyl anion, eta5-trimethyltincyclopentadienyl anion, eta5-triphenyltincyclopentadienyl anion, eta5-triphenylsilylcyclopentadienyl anion, and eta5-indenyl anion.
Each of the ligands L1 and L2 can be substituted by groups that do not interfere with the complexing action of the ligand to the metal atom or that do not reduce the solubility of the ligand to the extent that competing with the metal atom does not take place. Examples of substituting groups, all of which preferably have less than 30 carbon atoms and up to 10 hetero atoms selected from nitrogen, sulfur, non-peroxidic oxygen, phosphorus, arsenic, selenium, antimony, tellurium, silicon, germanium, tin, and boron, include hydrocarbyl groups such as methyl, ethyl, butyl, dodecyl, tetracosanyl, phenyl, benzyl, allyl, benzylidene, ethenyl, and ethynyl; cyclohydrocarbyl such as cyclohexyl; hydrocarbyloxy groups such as methoxy, butoxy, and phenoxy; hydrocarbylmercapto groups such as methylmercapto (thiomethoxy), phenylmercapto (thiophenoxy); hydrocarbyloxycarbonyl such as methoxycarbonyl and phenoxycarbonyl; hydrocarbylcarbonyl such as formyl, acetyl, and benzoyl; hydrocarbylcarbonyloxy such as acetoxy, and cyclohexanecarbonyloxy; hydrocarbylcarbonamido, for example, acetamido, benzamido; azo; boryl; halo, for example, chloro, iodo, bromo, and fluoro; hydroxy; cyano; nitro; nitroso; oxo; dimethylamino; diphenylphosphino; diphenylarsino; diphenylstibine; trimethylgermane; tributyltin; methylseleno; ethyltelluro; and trimethylsiloxy.
Ligands L1 and L2 independently can be a unit of a polymer. L1 for example, can be the phenyl group in polystyrene, or polymethylphenylsiloxane; or the carbazole group in polyvinylcarbazole. L2, for example, can be the cyclopentadiene group in poly(vinylcyclopentadiene). Polymers having a weight average molecular weight up to 1,000,000 or more can be used. It is preferable that 5 to 50% of the aromatic groups present in the polymer be complexed with metallic cations.
In addition to those described above, suitable anions, X, in Formula I, for use as the counterion in the ionic salts of the organometallic complex cation in the coating compositions are those in which X can be represented by the formula
xe2x80x83DQrxe2x80x83xe2x80x83(II)
wherein
D is a metal from Groups IB to VIIB and VIII or a metal or metalloid from Groups IIIA to VA of the Periodic Table of Elements (CAS notation),
Q is a halogen atom, hydroxyl group, a substituted or unsubstituted phenyl group, or a substituted or unsubstituted alkyl group, and
r is an integer having a value of 1 to 6.
Preferably, the metals are copper, zinc, titanium, vanadium, chromium, manganese, iron, cobalt, or nickel and the metalloids preferably are boron, aluminum, antimony, tin, arsenic, and phosphorus. Preferably, the halogen atom, Q, is chlorine or fluorine. Illustrative of suitable anions are B(phenyl)4xe2x88x92, B(phenyl)3(alkyl)xe2x88x92, where alkyl can be ethyl, propyl, butyl, hexyl and the like, BF4xe2x88x92, PF6xe2x88x92, AsF6xe2x88x92, SbF6xe2x88x92, FeCl4xe2x88x92, SnCl5xe2x88x92, SbFsOHxe2x88x92, AlCl4xe2x88x92, AlF6xe2x88x92, InF4xe2x88x92, TiF6xe2x88x92, ZrF6xe2x88x92, B(C6F5)4xe2x88x92, B(C6F3(CF3)2)4xe2x88x92.
Additional suitable anions, X, in Formula I, of use as the counterion in the ionic salts of the organometallic complex cations include those in which X is an organic sulfonate. Illustrative of suitable sulfonate-containing anions are CH3SO3xe2x88x92, CF3SO3xe2x88x92, C6H5SO3xe2x88x92, p-toluenesulfonate, p-chlorobenzenesulfonate and related isomers. Additional suitable anions include tris-(highly fluorinated alkyl)sulfonyl methide, bis-(highly fluorinated alkyl)sulfonyl imide, tris-(fluorinated aryl)sulfonyl methide, as described in U.S. Pat. No. 5,554,664, which patent is incorporated herein by reference. Preferably, the anions are BF4xe2x88x92, PF6xe2x88x92, SbF6xe2x88x92, SbF5OHxe2x88x92, AsF6xe2x88x92, SbCl6xe2x88x92, CF3SO3xe2x88x92, C(SO2CF3)3xe2x88x92, and N(SO2CF3)2xe2x88x92.
Organometallic salts are known in the art and can be prepared as disclosed in, for example, EPO Nos. 094,914, 094,915, 126,712, and U.S. Pat. Nos. 5,089,536, 5,059,701, 5,191,101, which are incorporated herein by reference. Also, disubstituted ferrocene derivatives can be prepared by the general procedure described in J. Amer. Chem. Soc., 1978, 100, 7264. Ferrocene derivatives can be oxidized to prepare the corresponding ferrocenium salts by the procedure described in Inorg. Chem., 1971, 10, 1559.
The preferred salts of organometallic complex cations useful in the compositions of the invention are derived from Formula I where L1 is chosen from the class of aromatic compounds, preferably based on benzene, and L2 is chosen from the class of compounds containing a cyclopentadienyl anion group, M is Fe and X is selected from the group consisting of tetrafluoroborate, hexafluorophosphate, hexafluoroarsenate, hexafluoroantimonate, tris-(trifluoromethylsulfonyl) methide, bis(trifluoromethylsulfonyl)imide, hydroxypentafluoroantimonate or trifluoromethanesulfonate. The most preferred salts of the organometallic complex cations useful in the invention are included in Formula I where only L1 is present, or where both L1 and L2 are present, M is Fe and X is selected from the group consisting of tetrafluoroborate, hexafluorophosphate, hexafluoroarsenate, hexafluoroantimonate, bis(trifluoromethylsulfonyl)imide, hydroxypentafluoroantimonate, trifluoromethanesulfonate, and tris-(trifluoromethylsulfonyl) methide. The organometallic complex cations can be used as mixtures and isomeric mixtures.
In the preferred compositions of the invention, salts of the organometallic complex cation include those disclosed in U.S. Pat. No. 5,089,536, which is incorporated herein by reference.
Examples of the preferred salts of organometallic complex cations useful in preparing the compositions of the invention include bis-(eta6-arene)iron complex cations, bis(eta5-cyclopentadienyl)iron complex cations, and (eta-5-cyclopentadienyl)iron arene complex cations such as:
bis-(eta6-cumene)iron(2+)hexafluoroantimonate,
bis-(eta6-durene)iron(2+)hexafluoroantimonate,
bis-(eta6-mesitylene)iron(2+)trifluoromethanesulfonate,
bis-(eta6-mesitylene)iron(2+)hexafluoroantimonate,
bis-(eta6-mesitylene)iron(2+)tris-(trifluoromethylsulfonyl)methide,
bis-(eta6-hexamethylbenzene)iron(2+)hexafluoroantimonate,
bis-(eta6-pentamethylbenzene)iron(2+)hexafluoroantimonate,
bis-(eta6-naphthalene)iron(2+)hexafluoroantimonate,
bis-(eta6-pyrene)iron(2+)hexafluoroantimonate,
(eta6-naphthalene)(eta5-cyclopentadienyl)iron(1+)hexafluoroantimonate,
(eta6-pyrene)(eta5-cyclopentadienyl)iron(1+)hexafluoroantimonate,
bis-(eta5-pentamethylcyclopentadienyl)iron(1+)hexafluoroantimonate,
bis-(eta5-emethylcyclopentadienyl)iron(1+)hexafluoroantimonate,
bis-(eta5-trimethylsilylcyclopentadienyl)iron(1+)hexafluoroantimonate,
bis-(eta5-indenyl)iron(1+)hexafluoroantimonate,
(eta5-cyclopentadienyl)(eta5-methylcyclopentadienyl)iron(1+)hexafluoroantimonate,
bis-(eta5-cyclopentadienyl)iron(1+)trifluoromethanesulfonate,
bis-(eta5-cyclopentadienyl)iron(1+)hexafluoroantimonate,
bis-(eta5-cyclopentadienyl)iron(1+)tris-(trifluoromethylsulfonyl)methide,
(eta6-xylenes(mixed isomers))(eta5-cyclopentadienyl)iron(1+)hexafluoroantimonate,
(eta6-xylenes(mixed isomers))(eta5-cyclopentadienyl)iron(1+)hexafluophosphate,
(eta6-xylenes(mixed isomers))(eta5-cyclopentadienyl)iron(1+)tris-(trifluoromethylsulfonyl)methide,
(eta6-xylenes(mixed isomers))(eta5-cyclopentadienyl)iron(1+)bis-(trifluoromethylsulfonyl)imide,
(eta6-m-xylene)(eta5-cyclopentadienyl)iron(1+)tetrafluoroborate,
(eta6-o-xylene(e)(eta5-cyclopentadienyl)iron(1+)hexafluoroantimonate,
(eta6-p-xylenes)(eta5-cyclopentadienyl)iron(1+)trifluoromethanesulfonate,
(eta6-toluene)(eta5-cyclopentadienyl)iron(1+)hexafluoroantimonate,
(eta6-mene)(eta5-cyclopentadienyl)iron(1+)hexafluoroantimonate,
(eta6-m-xylene)(eta5-cyclopentadienyl)iron(1+)hexafluoroantimonate,
(eta6-hexamethyl benzene )(eta 5-cyclopentadienyl)iron(1+)hexafluoroantimonate,
(eta6-mesitylene)(eta5-cyclopentadienyl-)iron(1+)hexafluoroantimonate,
(eta6-cumene)(eta5-cyclopentadienyl)iron(1+)hexafluorophosphate,
(eta6-cumene)(eta5-cyclopentadienyl)iron(1+)tris-(trifluoromethylsulfonyl)methide, and
(eta6-mesitylene)(eta5-cyclopentadienyl)iron(1+)pentafluorohydroxyantimonate.
In the polymerizable compositions of the present invention, the initiator salts can be present in a catalytically effective amount to initiate polymerization, generally in the range of 0.01 to 20 weight percent (wt %), preferably 0.1 to 10 wt %, of the curable composition; i.e., the total compositions excluding any solvent that may be present.
Accelerators of the present invention may be selected from four classes of materials. The active portions of these materials (see Formulae III to VI) can be part of a polymer or included as part of any component in the compositions of the invention.
Class 1 is described by the Formula III: 
Molecules of Class 1 comprise aromatic carboxyl containing molecules wherein each R1, independently, can be hydrogen or a group selected from chloro, iodo, bromo, fluoro, hydroxy, cyano, nitro, nitroso, carboxyl, formnyl, acetyl, benzoyl, trialkylsilyl, and trialkoxysilyl. Additionally, each R1, independently, can be a radical moiety selected from substituted and unsubstituted alkyl, alkenyl, alkynyl, and alkoxy groups containing up to 30 carbon atoms, or groups of one to four substituted or unsubstituted aromatic rings wherein two to four rings can be fused or unfused, or two R1s taken together can form at least one ring which is saturated or unsaturated and the ring can be substituted or unsubstituted. It is important that the substituting groups not interfere with the complexing action of the accelerating additive with the metal complex, or interfere with the cationic polymerization of the invention.
Examples of substituting groups that can be present in any R1 group, or can be attached directly to the ring, all of which preferably have less than 30 carbon atoms and up to 10 hetero atoms wherein heteroatoms can interrupt carbon chains to form, for example, ether or thio linkages selected from sulfur or non-peroxidic oxygen, include hydrocarbyl groups such as methyl, ethyl, butyl, dodecyl, tetracosanyl, phenyl, benzyl, allyl, benzylidene, ethenyl, and ethynyl; cyclohydrocarbyl groups such as cyclohexyl; hydrocarbyloxy groups such as methoxy, butoxy, and phenoxy; hydrocarbylmercapto groups such as methylmercapto (thiomethoxy), phenylmercapto (thiophenoxy); hydrocarbyloxycarbonyl such as methoxycarbonyl, propoxycarbonyl, and phenoxycarbonyl; hydrocarbylcarbonyl such as formyl, acetyl, and benzoyl; hydrocarbylcarbonyloxy such as acetoxy, and cyclohexanecarbonyloxy; perfluorohydrocarbyl groups such as trifluoromethyl and pentafluorophenyl; azo; boryl; halo, for example, chloro, iodo, bromo, and fluoro; hydroxy; carboxyl; cyano; nitro; nitroso; trimethylsiloxy; and aromatic groups such as cyclopentadienyl, phenyl, naphthyl and indenyl. Additionally, the R1s may be a unit of a polymer. Examples of suitable Class 1 accelerators include benzoic acid, salicylic acid, 2,3-dihydroxybenzoic acid, 2,3,4-trihydroxybenzoic acid, o-anisic acid, 2-ethoxybenzoic acid, o-toluic acid, m-toluic acid, p-toluic acid, haloaromatic acids such as 2-fluorobenzoic acid, 3-fluorobenzoic acid, 4-fluorobenzoic acid, 4-trifluoromethylbenzoic acid, phthalic acid, isophthalic acid, terephthalic acid, 4-butoxybenzoic acid, 4-nonyloxybenzoic acid, 4-octylbenzoic acid, 2-(p-toluoyl)benzoic acid, 2-nitrobenzoic acid, 3-nitrobenzoic acid, 4-nitrobenzoic acid, and 4-biphenyl carboxylic acid. Preferred additives from Class 1 are substituted benzoic and salicylic acids. The most preferred additives from Class 1 are benzoic acid, salicylic acid, and o-anisic acid.
Class 1 accelerators can be present in an amount in the range of 0.01 to 10.0 weight percent, preferably 0.1 to 4 weight percent of the total polymerizable composition.
Class 2 is described by the Formula IV: 
Molecules of Class 2 comprise those compounds having an aliphatic carboxylic moiety wherein each R2 can be the same or different as the other R2s and can be the same materials as those described for R1 in the Class 1 accelerators; additionally, two R2s taken together can form a carbonyl group. Examples of suitable accelerators of this class are formic acid, acetic acid, propionic acid, butyric acid, valeric acid, hexanoic acid, heptanoic acid, octanoic acid, nonanoic acid, decanoic acid, lauric acid, palmitic acid, stearic acid, chloroacetic acid, trifluoroacetic acid, 2-bromovaleric acid, glycolic acid, lactic acid, pyruvic acid, cyclobutanecarboxylic acid, cyclopentanecarboxylic acid, cyclohexanecarboxylic acid, 4-methyl-1-cyclohexanecarboxylic acid, phenylacetic acid, cyclohexylacetic acid, and multi-fuctional carboxylic acids such as oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azeleic acid, sebacic acid, undecanedioic acid, decanedicarboxylic acid, maleic acid, fumaric acid, trans-1,2-cyclohexanedicarboxylic and hexafluoroglutaric acid. Preferred additives from Class 2 are non-polymeric substituted and unsubstituted aliphatic carboxylic acids. The most preferred compounds from Class 2 are cyclohexanecarboxylic acid and phenylacetic acid. Class 2 accelerators can be present in an amount in the range of 0.01 to 10.0 weight percent, preferably 0.01 to 4 weight percent of the total polymerizable composition.
Class 3 is defined by the formula V: 
Molecules of Class 3 comprise esters of salicylic acid wherein each R1, independently, has the same definition as in Formula III and R3 can be selected from C1 to C10 substituted or unsubstituted alkyl groups, and groups of one to four substituted or unsubstituted aromatic rings wherein two to four rings can be fused or unfused. Examples of suitable accelerators of this class are methyl salicylate, ethyl salicylate, phenyl salicylate, 2-ethylhexylsalicylate, methyl 4-methoxysalicylate, and methyl 2,6-dihydroxy-4-methylbenzoate. Preferred additives from Class 3 are substituted and unsubstituted esters of salicylic acids. The preferred compound from Class 3 is methyl salicylate. Class 3 accelerators are particularly useful with bis-eta6-arene type organometallic salts and can be present in an amount in the range of 0.01 to 10.0 weight percent, preferably 0.1 to 4 weight percent of the total polymerizable composition.
Class 4 is defined by the formula VI: 
Molecules of Class 4 are defined by Formula VI wherein each R1, independently, has the same definition as in Formula III and R4 can be hydrogen or can be the same materials as described for R3 in Formula V. Examples of molecules of Class 4 are salicylaldehyde, o-hydroxyacetophenone, 2-hydroxybenzophenone, 2,4-dihydroxybenzophenone, 2,2xe2x80x2,4,4xe2x80x2-tetrahydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 5-chloro-2-hydroxybenzophenone, 2-hydroxy-4-octoxybenzophenone, 2-hydroxy-4-methoxy-4xe2x80x2-methylbenzophenone, and 2,2xe2x80x2-dihydroxy-4-methoxybenzophenone. Preferred additives from Class 4 are xcex1-hydroxy aromatic ketones. The preferred compounds from Class 4 are salicyladehyde, o-hydroxyacetophenone, and 2-hydroxybenzophenone. Class 4 accelerators are particularly useful with bis-eta6-arene type organometallic salts and can be present in an amount in the range of 0.01 to 10.0 weight percent, preferably 0.1 to 4 weight percent of the total polymerizable composition.
It should be noted that accelerators of different classes, or even within a class, may not be equally effective with any given initiator.
It is also within the scope of this invention to use one or more accelerating additives selected from different Classes 1 through 4. The different kinds of additives can be present in any proportion up to a total of 10.0 weight percent.
It can also be preferred and within the scope of this invention to add mono- or poly-alcohols as tougheners and flexibilizers to the polymerizable composition. The alcohol or polyol aids in chain extension and preventing over-crosslinking of the epoxide during curing.
Representative mono-alcohols can include methanol, ethanol, 1-propanol, 2-propanol, 2-methyl-2-propanol, 1-butanol, 2-butanol, 1-pentanol, neopentyl alcohol, 3-pentanol, 1-hexanol, 1-heptanol, 1-octanol, 2-phenoxyethanol, cyclopentanol, cyclohexanol, cyclohexylmethanol, 3-cyclohexyl-1-propanol, 2-norbomanemethanol, and tetrahydrofurfiryl alcohol.
Preferably, the polyols useful in the present invention have two to five, more preferably two to four, non-phenolic hydroxyl groups. Examples of useful polyols include, but are not limited to, 1,2-ethanediol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,3-butanediol, 2-methyl-1,3-propanediol, 2,2-dimethyl-1,3-propanediol, and 2-ethyl-1,6-hexanediol, 1,5-pentanediol, 1,6-hexanediol, 1,8-octanediol, neopentyl glycol, glycerol, trimethylolpropane, 1,2,6-hexanetriol, trimethylolethane, pentaerythritol, quinitol, mannitol, diethylene glycol, triethylene glycol, tetraethylene glycol, glycerine, 2-ethyl-2-(hydroxymethyl)-1,3-propanediol, 2-ethyl-2-methyl-1,3-propanediol, pentaerythritol, 2-ethyl-1,3-pentanediol, and 2,2-oxydiethanol, sorbitol, 1,4-cyclohexane dimethanol, 1,4-benzene dimethanol, 2-butene-1,4-diol, and polyalkoxylated bis-phenol A derivatives. Other examples of useful polyols are disclosed in U.S. Pat. No. 4,503,211, which is incorporated herein by reference.
Higher molecular weight polyols include the polyethylene and polypropylene oxide polymers in the molecular weight range of 200 to 20,000 such as the CARBOWAX polyethyleneoxide materials supplied by Union Carbide, caprolactone polyols in the molecular weight range of 200 to 5,000, such as the TONE polyol materials supplied by Union Carbide, polytetramethylene ether glycol in the molecular weight range of 200 to 4,000, such as the TERATHANE materials supplied by Dupont (Wilmington, Del.), hydroxyl terminated polybutadiene resins such as the POLY BD supplied by Elf Atochem, hydroxyl terminated polyester materials such as the DYNAPOL copolyester materials from Creanova Inc., Somerset, N.J., or equivalent materials supplied by other manufacturers.
The alcohol functional component can be present as a mixture of materials and can contain mono- and poly- hydroxyl containing materials. The alcohol is preferably present in an amount sufficient to provide an epoxy to hydroxy ratio in the composition between about 1:0.1 and 1: 1, more preferably between about 1:0.2 and 1:0.8, and most preferably between about 1:0.2 and 1:0.6.
It is also within the scope of this invention to incorporate thermoplastic oligomeric or polymeric resins to aid in the production of film-based compositions. These thermoplastics can make it easier to form films, i.e., are used as film-formers, and in some cases permit rework of a bond using an appropriate solvent. The thermoplastic resins include those that preferably have glass transition temperatures and/or melting points less than 120xc2x0 C. Useful thermoplastic resins are essentially free of groups that would interfere with the cationic polymerization of the cationically curable monomers. More particularly, useful thermoplastic resins are essentially free of nucleophilic groups, such as amine, amide, nitrile, sulfur or phosphorus functional groups, and free of metal-complexing groups such as carboxylic acid and sulfonic acid. Furthermore, suitable thermoplastic resins are soluble in solvents such as tetrohydrofuran (THF) or methylethylketone (MEK) and exhibit compatibility with the epoxy resin used.
This compatibility allows the blend of epoxy resin and thermoplastic resin to be solvent cast without phase separating. Nonlimiting examples of thermoplastic resins having these characteristics and useful in this invention include polyesters, co-polyesters, acrylic and methacrylic resins, polysulfones, phenoxy resins such as the PAPHEN materials available from Phenoxy Associates, Rock Hill, S.C., and novolac resins. It is also within the scope of this invention to use a blend of more than one thermoplastic oligomeric or polymeric resin in preparing compositions.
When it is desired to increase the pot-life of compositions of this invention, it can be useful to include a stabilizing additive. Useful pot-life stabilizing additives include Lewis basic, nitrogen-chelate ligands such as 1,10-phenanthroline, 2,2xe2x80x2-dipyridyl, and 2,4,6-tripyridytriazine; trialkyl, triaryl, tricycloalkyl, and trialkaryl amines, phosphines, phosphine oxides, phosphites, arsines, and stibines including triphenylphosphine, triphenylstibine, triphenylarsine, diethyl-o-toluidine, and triphenylphosphite; macrocyclic kryptands and crown ethers such as 12-CROWN-4, 15-CROWN-5, 18-CROWN-6, 21-CROWN-7, KRYPTOFIX 211, and KRYPTOFIX 222, all available from Aldrich Chemical Company, Milwaukee, Wis.; and Schiff base derivatives, which are generally made by the condensation of a ketone or aldehyde with a primary amine. Suitable stabilizing additives are described in U.S. Pat. No. 5,494,943 which is incorporated herein by reference.
A suitable initiation system that includes organometallic complex ionic salts described by Formula I, and at least one accelerator taken from Classes 1 through 4 contains those combinations that, upon application of sufficient energy, generally in the form of heat and/or light, will catalyze the polymerization of the compositions of the invention. The level of catalytic activity depends on various factors such as the choice of ligands and counterions in the organometallic salt and the selection of the type and amount of the at least one accelerator.
Temperature of polymerization and amount of initiator system used will vary depending on the particular polymerizable composition used and the desired application of the polymerized product.
Addition of a silane coupling agent is optional in the preparation of cured compositions of the invention. Preferably the silane coupling agent is added to the polymerizable composition to improve adhesion when at least one substrate surface is glass, an oxide, or any other surface that would benefit from the addition of a silane coupling agent. When present, a silane coupling agent contains a functional group that can react with an epoxy resin, e.g., 3-glycidoxypropyltrimethoxylsilane.
Solvents, preferably organic, can be used to assist in dissolution of the initiator system in the polymerizable monomers, and as a processing aid. It may be advantageous to prepare a concentrated solution of the organometallic complex salt in a small amount of solvent to simplify the preparation of the polymerizable composition. Useful solvents are lactones, such as gamma-butyrolactone, gamma-valerolactone; and epsilon-caprolactone; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclopentanone and cyclohexanone; sulfones, such as tetramethylene sulfone, 3-methylsulfolane, 2,4-dimethylsulfolane, butadiene sulfone, methyl sulfone, ethyl sulfone, propyl sulfone, butyl sulfone, methyl vinyl sulfone, 2-(methylsulfonyl)ethanol, 2,2xe2x80x2-sulfonyldiethanol; sulfoxides, such as dimethyl sulfoxide; cyclic carbonates such as propylene carbonate, ethylene carbonate and vinylene carbonate; carboxylic acid esters such as ethyl acetate, methyl cellosolve acetate, methyl formate; and other solvents such as methylene chloride, nitromethane, acetonitrile, glycol sulfite and 1,2-dimethoxyethane (glyme). In some applications, it may be advantageous to adsorb the initiator onto an inert support such as silica, alumina, clays, as described in U.S. Pat. No. 4,677,137, which is incorporated herein by reference.
Suitable sources of heat to cure the compositions of the invention include induction heating coils, ovens, hot plates, heat guns, infrared sources including lasers, microwave sources. Suitable sources of light and radiation include ultraviolet light sources, visible light sources, and electron beam sources.
Suitable substrates useful to provide articles of the invention include, for example, metals (for example, aluminum, copper, cadmium, zinc, nickel, steel, iron, silver), glass, paper, wood, various thermoplastic films (for example, polyethylene terephthalate, plasticized polyvinyl chloride, polypropylene, polyethylene), thermoset films (for example, polyimide), cloth, ceramics and cellulosics, such as cellulose acetate.
Adjuvants may optionally be added to the compositions such as colorants, abrasive granules, anti-oxidant stabilizers, thermal degradation stabilizers, light stabilizers, conductive particles, tackifiers, flow agents, bodying agents, flatting agents, inert fillers, binders, blowing agents, fungicides, bactericides, surfactants, plasticizers, rubber tougheners and other additives known to those skilled in the art. They also can be substantially unreactive, such as fillers, both inorganic and organic. These adjuvants, if present are added in an amount effective for their intended purpose.
Compositions of this invention are useful to provide abrasion-resistant or protective coatings to articles. The compositions are useful as encapsulants, sealants, molded articles or three-dimensional objects such as those generated by stereolithography. They are also useful as adhesives, including hot melt, pressure sensitive, and structural adhesives, and as binders for abrasives. The compositions may also be useful in imaging applications such as photoresist and photolithography.
In general, a composition""s physical properties, i.e., hardness, stiffness, modulus, elongation, strength, etc., is determined by the choice of the epoxy resin, and if an alcohol containing material is used, the ratio of epoxy to alcohol and the nature of the alcohol. Depending on the particular use, each one of these physical properties of the system will have a particular optimum value. Generally, the cured material from a higher epoxy/alcohol ratio is stiffer than from a lower epoxy/alcohol ratio. Generally, for an epoxy/alcohol composition, a shorter chain polyol yields a cured composition that is stiffer than when using a longer chain polyol. The stiffness of a composition can also be increased by using a shorter chain monofunctional alcohol to replace a polyol. Epoxy/alcohol mixtures generally cure faster than epoxy-only compositions. Cycloaliphatic epoxies cure more rapidly than glycidyl ether epoxies. Mixtures of these two types of epoxies can be used adjust the cure rate to a desired level.
To prepare a coated abrasive article using the materials of the subject invention, abrasive particles must be added to the curable composition. The general procedure is to select a suitable substrate such as paper, cloth, polyester, etc., coat this substrate with the xe2x80x9cmake coat,xe2x80x9d which consists of the curable composition, applying the abrasive particles, and then curing by the application of a source of energy. A xe2x80x9csize coat,xe2x80x9d which cures to a harder material than the make coat, is then coated over the make coat and cured. The size coat serves to lock the abrasive particles in place. For this and other applications the coating preferably is provided by methods such as bar, knife, reverse roll, extrusion die, knurled roll, or spin coatings, or by spraying, brushing, or laminating.
To prepare a structural/semi-structural adhesive, the curable composition could contain additional adjuvants such as silica fillers, glass bubbles and tougheners. These adjuvants add toughness to, and reduce the density of, the cured composition. Generally shorter chain polyols would be used to give toughness through chain extension of the cured epoxy. A chain diol that is too long generally would produce too soft a cured composition that would not have the strength needed for structural/semi-structural applications. Using polyols having high hydroxyl functionality greater than three could produce an overcrosslinked material resulting in a brittle adhesive.
To prepare magnetic media using the materials of the subject invention, magnetic particles must be added to the curable composition. Magnetic media need to be coated onto a suitable substrate, generally a polymeric substrate like polyester. Generally the coatings are very thin so that sufficient carrier solvent must be added to allow the production of a suitably thin, even coating. The coating must cure rapidly so a fast initiator system and curable materials must be chosen. The cured composition must have a moderately high modulus so the curable materials must be selected appropriately.
To prepare a clear abrasion resistant coating from the materials of the subject invention, two important criteria for selecting the composition are clarity and toughness of the cured composition. Generally, particulate adjuvants would not be added since they would reduce the gloss and clarity of the cured composition. Optionally, pigments or dyes could be added to produce a colored film.
To prepare an electrically conductive adhesive, the curable composition is filled with conductive particles to the level that provides conduction through the adhesive between the desired contact points. One class of conductive adhesives is often referred to as xe2x80x9cz-axis adhesivesxe2x80x9d or as xe2x80x9canisotropically conductive adhesives.xe2x80x9d This class of adhesive is filled with conductive particles to the level that provides conduction between contact points in the z-axis but not the x-y plane of the adhesive. Such z-axis adhesives are often produced as a thin film adhesive on a carrier substrate, such as a polymer film. A description of materials suitable for z-axis adhesives is disclosed in U.S. Pat. No. 5,362,421, which is incorporated herein by reference.
Molded articles are made by means known to those skilled in the art, as, for example, by reaction injection molding, casting, etc.